Ryou Asai is the pen name of Ryou Sasai (佐々井 遼), a novelist who debuted in 2010 with Kirishima, Bukatsu Yamerutte yo. That work won him the 22nd Shousetsu Subaru Newcomer Award and has been adapted into a live-action film which won the Picture of the Year award at the 36th Japan Academy Prize.

Asai is a fan of the works of Studio Ghibli. The cover art of his 2013 novel Sekai Chizu wo Shitagaki was drawn by Ghibli animator Katsuya Kondou.

British literary magazine Granta named Asai one of the Best Young Japanese Novelists of 2016.